#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int vis[128] = { 0 };
	char tmp, c[100] = { 0 }, s[100] = { 0 };
	scanf("%s", c);
	int top = 0;
	int len = strlen(c);
	for (int i = 0; i < len; i++)
	{
		tmp = c[i];
		if (vis[c[i]] == 0)
		{
			vis[c[i]] = 1;
			s[top] = c[i];
			top++;
		}
	}
	printf("%s", s);
	return 0;
}